1. Field of the Invention
The present invention relates to a manufacturing method for a photoelectric conversion apparatus and a photoelectric conversion apparatus.
2. Description of the Related Art
A structure of a photoelectric conversion apparatus in which multiple photoelectric conversion elements are arranged for one microlens (hereinafter, may be referred to as an ML) has been known (Japanese Patent Laid-Open No. 2013-84742). In such a photoelectric conversion apparatus, light is condensed onto multiple photoelectric conversion elements using a single ML, and focus detection is performed using signals of the multiple photoelectric conversion elements. A method for forming an electric charge accumulation region in each photoelectric conversion element by performing ion implantation using a mask pattern having an independent resist aperture region for each electric charge accumulation region has been known.
An electric charge accumulation region included in a photoelectric conversion element greatly affects, in particular, the performance of signal detection. Therefore, it is required to highly accurately form an electric charge accumulation region having desired properties.
In a structure disclosed in Japanese Patent Laid-Open No. 2013-84742 in which multiple N-type electric charge accumulation regions are isolated by a P-type impurity region of a conductive type opposite a conductive type of the electric charge accumulation regions, the P-type impurity region is formed in close proximity to the electric charge accumulation regions. Therefore, the distance between the P-type impurity region and each of the electric charge accumulation regions greatly affects the accumulation capacity of signal electric charges in the electric charge accumulation region. In manufacturing a photoelectric conversion element having the structure disclosed in Japanese Patent Laid-Open No. 2013-84742, in a case where an independent aperture is formed for each region of a mask in which an electric charge accumulation region is to be formed and ion implantation is performed, a displacement of the electric charge accumulation region with respect to a desired formation position occurs. With such a displacement, variations in the distance between an electric charge accumulation region and a P-type impurity region increase, and variations in the capacity of the electric charge accumulation region thus increase.
The above-mentioned point is particularly an issue to be addressed for a photoelectric conversion apparatus including multiple photoelectric conversion elements for a single ML, as disclosed in Japanese Patent Laid-Open No. 2013-84742. A reason for this issue is that the number of photoelectric conversion elements in a photoelectric conversion apparatus in which multiple photoelectric conversion elements are arranged for a single ML is greater than the number of photoelectric conversion elements in a photoelectric conversion apparatus in which a single photoelectric conversion element is arranged for a single ML. There is a tendency in which in accordance with an increase in the number of photoelectric conversion elements, the size of an electric charge accumulation region included in each photoelectric conversion element becomes smaller than the size of an electric charge accumulation region in a photoelectric conversion apparatus in which a single photoelectric conversion element is arranged for a single ML. In addition, in accordance with a miniaturization in the size of an electric charge accumulation region, in formation of the electric charge accumulation region using a mask pattern, the rate of the amount of displacement of a mask pattern relative to the size of the electric charge accumulation region in a substrate in-plane direction increases. Therefore, variations in the capacity of an electric charge accumulation region caused by variations in the relative positional relationship between the electric charge accumulation region and a P-type impurity region increase.
The present invention reduces, in manufacturing a photoelectric conversion apparatus in which multiple photoelectric conversion elements are arranged for a single ML, variations in the relative positional relationship between an electric charge accumulation region in each photoelectric conversion element and an isolation region arranged between the electric charge accumulation regions.